Multifunctional CNT-engineered structures

ABSTRACT

Various applications for structured CNT-engineered materials are disclosed herein. In one application, systems are disclosed, wherein a structured CNT-engineered material forms at least part of an object capable of providing its own structural feedback. In another application, systems are disclosed, wherein a structured CNT-engineered material forms at least part of an object capable of generating heat. In yet another application, systems are disclosed, wherein a structured CNT-engineered material forms at least part of an object capable of functioning as an antenna, for example, for receiving, transmitting, absorbing and/or dissipating a signal. In still another application, systems are disclosed, wherein a structured CNT-engineered material forms at least part of an object capable of serving as a conduit for thermal or electrical energy.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims the benefit of priorityto U.S. patent application Ser. No. 15/067,062, filed on Mar. 10, 2016,which is a continuation of and claims the benefit of priority to U.S.patent application Ser. No. 14/808,949, filed on Jul. 24, 2015, which isa continuation of and claims the benefit of priority to U.S. patentapplication Ser. No. 13/014,603, filed on Jan. 26, 2011, now U.S. Pat.No. 9,091,657, which claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 61/298,385, entitled “MultifunctionalCNT-Engineered Structures,” filed on Jan. 26, 2010. The entire contentof each application is hereby incorporated by reference in its entirety.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with Government support under Contract No.FA9550-09-C-0165 awarded by the Air Force Office of Scientific Research.The Government has certain rights in the invention.

BACKGROUND

Advanced composite materials are increasingly used in applications suchas aerospace structure design due to superior stiffness, strength,fatigue resistance, corrosion resistance, etc. In many instances, theuse of advanced composite materials may also greatly reduce the numberof parts. Composites present challenges for inspection however due toheterogeneity, anisotropy, and the fact that damage is often subsurface.Despite success in the laboratory setting, many non-destructive testingand monitoring techniques, are impractical for real-world inspection oflarge-area integrated composite structures, for example, due to the sizeand complexity of the required support equipment. In addition, manycomponents that need frequent monitoring typically reside in limitedaccess areas that would require breaking of factory seals andcalibrations to manually inspect. It is clear that new approaches forinspection are necessary.

To facilitate inspection, a structure may advantageously incorporate adistribution of sensors to provide feedback for or on the structure.Such feedback may include event notifications (such as for impact),structural integrity, usage, shape, and/or configuration. Conventionalsensors, however, may add weight to a structure and can presentelectrical connectivity and mechanical coupling challenges. Conventionalsensors often present reliability risks (i.e., many sensors fail and/ormalfunction in advance of the structure they are monitoring). Thusstructures formed from materials which are capable in themselves ofproviding feedback are highly desirable. Examples of such integratedfeedback materials include but are note limited to materials that changeresistance values as they are strained, materials that can provideactuation through phase change, ablative materials, and materials thatcan store energy.

Carbon nanotubes (CNTs) can posses exceptional mechanical stiffness(e.g., ˜1 TPa) and strength, as well as excellent electricalconductivity (e.g., ˜1000× copper) and piezoresistivity (resistivitychange with mechanical strain). Presently, however, it is not possibleto produce large specimen (>5 mm) purely of CNTs. Furthermore, due toissues such as agglomeration and poor dispersion, only marginalimprovements in mechanical properties are observed for hybrid compositeswhen CNTs are introduced into the bulk matrix. Somewhat better resultscan be achieved using nanoscale modification of the interface betweencomposite plies, by growing CNTs on the surface of cloth or placingunaligned CNTs at low volume fractions on fibers. However, theseapproaches do not significantly improve electrical conductivity and thuslimit many practical applications.

SUMMARY

New and advantageous applications for structured CNT-engineeredmaterials are disclosed herein. In some embodiments, systems aredisclosed, wherein a structured CNT-engineered material forms at leastpart of an object capable of providing its own structural feedback, forexample, structural health feedback. Feedback may also include spatialinformation, for example, for localizing a point of impact or a damagedarea of the object. In other exemplary embodiments, systems aredisclosed, wherein a structured CNT-engineered material forms at leastpart of an object capable of generating heat. The generated heat may beused, for example, for thermographic imaging of the object or otherpurposes, such as de-icing or maintaining a certain temperature. In yetother exemplary embodiments, systems are disclosed wherein a structuredCNT-engineered material forms at least part of an object capable offunctioning as an antenna, for example, for receiving, transmitting,absorbing and/or dissipating a signal. In still other embodiments,systems are disclosed, wherein a structured CNT-engineered materialforms at least part an object capable of serving as a conduit forthermal or electrical energy.

In exemplary embodiments, systems may include a detection system and/ora control system operationally coupled to a structured CNT network of anobject at least part of a structured CNT-engineered material. Forexample, one or more electrode arrays may be used to couple thestructured CNT network to the detection system and/or the controlsystem. In exemplary embodiments, the detection and/or control systemmay be implemented in whole or in part using computing environment, orprocessor as described herein. In some embodiments, the detection systemmay be used to detect electrical conductivity/resistivity across the CNTnetwork, for example, across one or more electrode pairs. In otherembodiments, the detection system may be used to detect propagation ofan electrical or acoustic signal across the CNT network. In someembodiments, the control system may be used to power the CNT-network,for example, induce a voltage or current across one or more electrodepairs, to generate heat.

In exemplary embodiments a system is disclosed including an objecthaving a portion formed from a structured CNT-engineered material and acontrol system operationally coupled to the structured CNT network ofthe CNT-engineered material and configurable or programmable to drivethe structured CNT network with electrical energy to maintain or changea temperature of the object. In some embodiments, driving the structuredCNT network includes inducing a current through the CNT network. Inother embodiments, driving the structured CNT network includes inducinga voltage across the CNT network. In exemplary embodiments, maintainingthe temperature of the object includes maintaining the temperature ofthe object at or above a selected temperature. In exemplary embodimentsthe object is used to maintain or change a temperature of a substanceassociated with the object (for example, a substance on, in or otherwisethermally coupled to the object). In some embodiments the temperature ofthe substance may be maintained at or above a selected temperature so asto prevent a phase transition thereof. In other embodiments, thetemperature of the substance may be changed so as to induce a phasetransition thereof. In some embodiments, the control system may beconfigured to change a temperature of the object so as to de-ice theobject. In other embodiments, the control system may be configured tochange a temperature of the object so as to prevent icing thereof. Insome embodiments, the control system may be configured to change atemperature of the object so as to so as to melt a frozen fluid in thesystem or prevent a fluid in the system from freezing. In someembodiments, the system may include a thermographic imaging system forthermographically imaging the object, for example, to detect a propertyor characteristic of the object related to structural health of theobject. In other embodiments, The system may include a detection systemfor providing temperature feedback for the object and/or itssurroundings. In exemplary embodiments, the control system may beconfigured to adjust power to the CNT-network based on the temperaturefeedback. In some embodiments the temperature feedback may includetemperature change rate for the object or for a substance associatedwith the object. In exemplary embodiments the detection system may beconfigured to determine a property or characteristic, for example,presence/absence, amount, constitution, or the like, of a substance, forexample ice, associated with the object based on a temperature changerate of the object or of the substance.

In exemplary embodiments a system is disclosed including an objecthaving a portion formed from a structured CNT-engineered material and aconfigurable or programmable detection system operationally coupled tothe CNT network of the structured CNT-engineered material to detect achange in a physical property or characteristic of the object.Advantageously the physical property or characteristic may includespatial data, relating for example, to one or more of location, size,shape and distribution of the physical property or characteristic. Insome embodiments, detecting the change in the physical property orcharacteristic of the object may include detecting a change inelectrical conductivity or resistance across the CNT network. Inexemplary embodiments, a structural change to the CNT network, forexample, on account of damage to the object, a change in shape of theobject, or the like, may be detected based on the change in electricalconductivity or resistance. In other embodiments, a piezoresistiveresponse of the CNT-network, for example on account of damage to theobject, a change in shape of the object, propagation of an acoustic waveacross the object or the like, may be detected based on the change inelectrical conductivity or resistance. In yet other embodiments, a phasechange of a substance on a surface of the object may be detected basedon changes in surface conductivity or resistance. In some embodiments,detecting the change in the physical property or characteristic of theobject may include isolating a electronic signal by applying one or morefilters in the frequency domain. In exemplary embodiments, the physicalproperty or characteristic of the object may be related to propagationof an acoustic wave across the object. Thus, in some embodiments, thedetection system may be configured to detect the propagation of anacoustic wave across the object. In exemplary embodiments the physicalproperty or characteristic of the object is related to structural healthof the object. Thus, in some embodiments the detection system may beconfigured to detect damage to the object and/or determine severity,location, size, shape and distribution for the damage. In otherembodiments the detection system may be configured to detect and/orlocate an impact to the object. In exemplary embodiments, the detectionsystem may be configured to detect and/or locate an impact to the objectbased on detection of the propagation of an acoustic wave generated bythe impact. In exemplary embodiments, the physical property orcharacteristic of the object may be related to shape of the object.Thus, for example, the detection system may provide feedback on theshape of a configurable object. In exemplary embodiments, the detectionsystem may be operationally coupled relative to the CNT network via oneor more electrode arrays, for example, defining a plurality of electrodepairs across the CNT network.

In exemplary embodiments a system is disclosed including an objecthaving a portion formed from a structured CNT-engineered material andone or more electrode arrays defining a plurality of electrode pairsacross the CNT network. In some embodiments, data from each electrodepair may correspond to a different region of the object. For example,the plurality of electrode pairs may define a detection grid across theCNT network. In exemplary embodiments, the system may include one ormore multiplexing switches for combining measurements from a pluralityof the electrode pairs. In some embodiments, the one or more electrodearrays may be formed as traces using a direct-write technique. In otherembodiments, the one or more electrode arrays may be formed usingexternally applied contacts. In some embodiments, the one or moreelectrode arrays may be formed using a flexible circuit. In exemplaryembodiments, the one or more electrode arrays may be formed using aplurality of traces or layers. for example, wherein the traces are wovenor braided.

In exemplary embodiments, a system is disclosed including an objecthaving a portion formed from a structured CNT-engineered material thatincludes a structured CNT network, wherein the CNT network forms anantenna, for example, wherein the antenna is configured to receive,transmit, absorb and/or dissipate a signal, for example anelectromagnetic signal (such as a radio signal or radar signal) anacoustic signal (such as a sonar signal) or an electrical signal (suchas lightning). In exemplary embodiments the CNT network may beselectively patterned for specific applications, for example, forreceiving or transmitting a radio signal, receiving or absorbing a radarsignal, receiving or absorbing a sonar signal, or dissipating lightning.

In exemplary embodiments a system is disclosed including an objecthaving at least a portion formed from a structured CNT-engineeredmaterial that includes a structured CNT network, wherein the CNT networkis configured to function as a conductor for conveying thermal orelectrical energy to or from one or more components coupled to theobject. In some embodiments, the CNT network may be configured totransfer power to or from the one or more components, for example,wherein one of the components is a power source such as a solar powersource. In other embodiments, the CNT network may be configured toconvey communications to or from one or more components. In exemplaryembodiments, the object may convey thermal energy so as to function as aheat sink, thermal radiator panel, thermal shield or the like.

Additional features, functions and benefits of the disclosed systemswill be apparent from the description which follows, particularly whenread in conjunction with the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exemplary morphology for fuzzy fiber reinforcedcomposites, according to the present disclosure.

FIG. 2 depicts fibers for the fuzzy fiber reinforced composite of FIG.1, before and after growth of a structured CNT network, according to thepresent disclosure.

FIG. 3 depicts an exemplary system including an object at least portionof which is formed from a structured CNT-engineered materialcharacterized by a structured CNT network, according to the presentdisclosure.

FIG. 4 depicts exemplary direct write traces produced using a plasmaflame spray, according to the present disclosure.

FIG. 5 depicts exemplary direct write traces produced using jettedatomized deposition, according to the present disclosure.

FIG. 6 depicts an exemplary flexible frame, according to the presentdisclosure.

FIG. 7 depicts in-plane and though-plane conductivity reading forexemplary objects (specimens 1-3) formed from a structuredCNT-engineered material and impacted at 15, 30 and 45 ft-lbs,respectively, according to the present disclosure.

FIG. 8 depicts thermographic imaging of an exemplary object at leastpart of which is formed of a structured CNT-engineered materialincluding a structured CNT network, after heating the object using thestructured CNT network, according to the present disclosure.

FIG. 9 depicts temperature as a function of time over the first thirtyseconds of heating exemplary objects at least part of which is formed ofa structured CNT-engineered material including a structured CNT networkfor different ice thickness coating on the objects (no ice, 1, 2, and 3mm) and different starting temperatures (−5, −10 and −15° C.), accordingto the present disclosure.

FIG. 10 depicts temperature rate of change as a function of icethickness for the exemplary objects and data of FIG. 9, according to thepresent disclosure.

FIG. 11 depicts an exemplary implementation of an ice detectiontechnique, wherein ice was detected, according to the presentdisclosure.

FIG. 12 depicts an exemplary implementation of an ice detectiontechnique, wherein ice was not detected, according to the presentdisclosure.

FIG. 13 depicts de-icing of exemplary objects at least part of which areformed of a structured CNT-engineered material including a structuredCNT network, wherein the objects are heated using the structured CNTnetwork, according to the present disclosure.

FIG. 14 steady state temperature as a function of power to theCNT-network and power as a function of applied voltage for an exemplaryobject at least part of which are formed of a structured CNT-engineeredmaterial including a structured CNT network, according to the presentdisclosure.

FIG. 15 anti-icing using the exemplary object of FIG. 14, according tothe present disclosure.

FIG. 16 depicts an exemplary computing environment according to thepresent disclosure.

FIG. 17 depicts an exemplary network environment, according to thepresent disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENT(S)

Structured CNT-engineered materials represent a relatively new class ofmaterials, exemplary embodiments of which are described, inter alia, inU.S. Pat. No. 7,537,825, PCT Application No. PCT/US2007/011913(WO/2008/054541), U.S. application Ser. No. 11/895,621 (US 2008/0075954)and U.S. application Ser. No. 12/227,516 (US 2009/0311166). See also,Garcia E. J., Wardle, B. L., Hart J. A. and Yamamoto N., “Fabricationand multifunctional properties of a hybrid laminate with aligned carbonnanotubes grown in situ,” Composite Science and Technology, v. 68, pp.2034-41, 2008. Each of the foregoing patent and non-patent references ishereby incorporated herein to the extent that it is not inconsistentwith the present disclosure. Structured CNT-engineered materials arediscussed in greater detail below.

In general, structured CNT-engineered materials may advantageouslyinclude structured CNT networks, for example, wherein CNTs arestructured relative to one another and/or with respect to a substrate.Thus, structured CNT-engineered materials may be distinguished fromconventional CNT composites, for example, where the in conventional CNTcomposites CNTs are dispersed or grown such that the orientations ofCNTs are substantially random in nature. As used herein, structuredCNT-engineered materials are not limited to any particular CNT networkmorphology or CNT group morphology. For example, in some embodiments, aplurality of CNTs may be substantially aligned relative to one another.In other embodiments, a plurality CNTs may be substantially alignedrelative to a substrate, for example, aligned radially relative to afiber in a fiber reinforced composite.

It will be appreciated by one of ordinary skill in that are that groupsof CNTs may include same or different alignments. For example, in someembodiments, a first plurality of CNTs (such as may be associated with afirst substrate) may be aligned in a first direction and a secondplurality of CNTs (such as may be associated with a second substrate)may be aligned in a second direction (which may be the same direction ora different direction than the first direction). In other embodiments, afirst plurality of CNTs may be substantially aligned relative to a firstsubstrate (for example, substantially perpendicular to a surface of thefirst substrate) and a second plurality of CNTs may be substantiallyaligned relative to a second substrate (for example, substantiallyperpendicular to a surface of the second substrate). In either case, thefirst plurality of CNTs may advantageously interact with the secondplurality of CNTs to provide a contiguous CNT network, for example,between the first and second substrates.

In exemplary embodiments, structured CNT-engineered materials may behybrid composites such as fiber reinforced hybrid composites. Fiberreinforced hybrid composites may include, for example, reinforcingfibers such as aluminum fibers (diameter typically of order microns) andstructured CNTs (for example, with mass fraction between 0.5 and 2.5%)organized within a matrix (for example, a polymer matrix). Asillustrated in FIGS. 1 and 2, CNTs may be structured with respect to thefibers (for example, grown in situ and radially aligned relative to thefibers) to form “fuzzy fibers” (FFs). Adjacent CNTs, for example, CNTsassociated with adjacent FFs, may interact, for example, bind, to formthe structured CNT network throughout the composite. Advantageously, thestructured CNT network may be substantially uniform and contiguous.Composites formed using FFs may be referred to as fuzzy fiber reinforcedcomposites (FFRCs).

Structured CNT-engineered materials may advantageously provide forimproved electrical conductivity over conventional CNT and non-CNTcomposites. For example, whereas conventional composites typicallyexhibit electrical conductivity on the order of 10⁻⁷ to 10⁻¹⁰ S/mm,structured CNT-engineered materials may typically exhibit electricalconductivity on the order of 10⁻¹ to 10⁻² S/mm. Thus, in exemplaryembodiments, structured CNT-engineered materials may exhibitconductivity greater than 10⁻⁵ S/mm and in some embodiments greater than10⁻⁴ S/mm or less than 10⁻³ S/mm. FFRCs developed through MassachusettsInstitute of Technologies Nano-Engineered Composite Aerospace Structures(NECST) consortium have been demonstrated to have substantially greaterelectrical conductivity (on the order of 10⁸ times greater forthru-thickness and 10⁶ times greater for in-plane) compared to similarcomposites without CNTs. Due to the structured CNT network, structuredCNT-engineered materials may advantageously be substantiallytransversely isotropic with respect to electrical conductivity. In someembodiments, depending on morphology, structured CNT-engineeredmaterials may be substantially isotropic with respect to electricalconductivity. The improved electrical conductivity of structuredCNT-engineered materials is also particularly advantageous, for reducinga signal-to-noise ratio and achieving accurate/reliable detection and/ormeasurement of relatively small changes in resistance.

New and advantageous applications for structured CNT-engineeredmaterials are disclosed herein. In some embodiments, systems aredisclosed, wherein a structured CNT-engineered material may be used toconstruct an object capable of providing its own structural feedback,for example, structural health feedback. Advantageously, feedback mayinclude spatial information, for example, for localizing a damaged areaof the object. In other exemplary embodiments, systems are disclosed,wherein a structured CNT-engineered material may be used to construct anobject capable of generating heat. The generated heat may be used, forexample, for thermographic imaging of the object or other purposes, suchas de-icing or maintaining a certain temperature. In yet other exemplaryembodiments, systems are disclosed wherein a structured CNT-engineeredmaterial may be used to construct an object capable of functioning as anantenna, for example, for receiving, transmitting, absorbing and/ordissipating a signal. In still other embodiments, systems are discloseswherein, a structured CNT-engineered material may be used to constructan object capable of serving as a conduit for thermal or electricalenergy.

Referring now to FIG. 3, an exemplary system 300, according to thepresent disclosure, is depicted. The exemplary system 300 generallyincludes an object 310 at least portion of which is formed from astructured CNT-engineered material characterized by a structured CNTnetwork. It is noted that object 310 may be any object and maystand-alone or be a component (structural or non-structural) of a largerassembly. By way of example, object 310 may be a wing of an aircraft, asiding of a building or a casing for a medical device.

In general, system 300 may include one or more electrodes operationallycoupled relative to the structured CNT network, for example fordetecting an electrical signal across the network. In exemplaryembodiments system 300 may include one or more one or more electrodearrays defining a plurality of electrode pairs across the structured CNTnetwork. The electrode pairs may advantageously define a grid across thestructured CNT network. In exemplary embodiments, point wise steppingmay be used to select and cycle through each of the electrode pairs. Inother embodiments, a multiplexing switch may be used to combinemeasurements from a plurality of electrode pairs.

As depicted in FIG. 3, the system 300 includes pair of electrode arrays320A and 320B positioned on opposite sides of the structured CNT networkwherein one of the electrode arrays 320A includes a plurality of“active” electrode columns (for example, columns 322A and 324A) and theother electrode array 320B includes a plurality of “passive” (i.e.,grounded) electrode rows (for example rows 322B and 324B). The columnsand rows are each coupled by a multiplexing switch 330A or 330B. Theelectrode columns and rows advantageously define a detection grid,wherein each column/row electrode pair defines a point on the grid. Byselecting and cycling through column/row electrode pairs, measurements,including spatial data, may be obtained for each of the grid points. Itis also noted that in plane data may also be obtained, for example byselecting a pair of column electrodes or a pair of row electrodes formeasurement. In some embodiments, a plurality of “active” electrodes maybe aligned in rows and a plurality of “passive” (i.e., grounded)electrodes may be aligned in columns.

In exemplary embodiments, the electrode arrays 320A and 320B may be usedto couple the structured CNT network to a detection system 340 and/or acontrol system 350 which may be implemented in whole or in part using acomputing environment, or processor as described herein. In someembodiments the detection system 340 may be used to detect electricalconductivity/resistivity across one or more electrode pairs. In otherembodiments the detection system 340 may be used to detect an electricalsignal across the one or more electrode pairs. In some embodiments, thecontrol system 350 may be used to power, for example, induce a voltageor current across, one or more electrode pairs, for example to generateheat.

In exemplary embodiments, the detection system 340 may be configuredand/or programmed to detect a change in a physical property orcharacteristic of the object 310. In some embodiments the change in thephysical property or characteristic of the object 310 may be determinedby detecting a change in electrical conductivity/resistivity across thestructured CNT network, (for example across, one or more electrodepairs). The changes in conductivity/resistivity may be on account ofchanges in the structured CNT network structure (for example, due todamage to object 310) or on account of a piezoresistive response of thestructured CNT network structure (for example, due to propagation of amechanical wave, a change of shape of the object 310, or structuraldamage to the object 310). In some embodiments, the detection system isconfigured and/or programmed to detect a phase change of a substance(for example, ice) on a surface of the object based on changes insurface conductivity or resistance.

In exemplary embodiments the physical property or characteristic of theobject 310 may be related to the structural health of the object 310.Thus, for example, damage to the object 310 may be detected based on adetected change in conductivity/resistivity. Using a plurality ofelectrode pairs, for example, the electrode grid described above,spatial data for the damage may also be determined, for example relatingto one or more of location, size, shape and distribution of the damage.

In other exemplary embodiments, the physical property or characteristicof the object may be related to the shape of the object 310. Thus, forexample, a change to the shape of the object 310 may be detected basedon a detected change in conductivity/resistivity. More particularly, achange in shape of the object 310 can cause a piezoresistive responsewhich results in the change in conductivity/resistivity. This may beparticularly useful for applications where the shape of the object 310is configurable. In particular, the detection system 340 may provideuseful feedback, to facilitate configuring the shape of the object 310.

In exemplary embodiments, changes in electrical conductivity/resistivityof the structured CNT network may also be used to detect and monitor,for example, based on a piezoresistive response, the propagation of amechanical wave, for example an acoustic wave, through/across the object310. Thus, the detection system 340 may be configured to detect animpact to the object 310 based on detection of a mechanical waveproduced by the impact. Using a plurality of electrode pairs, spatialdata for the impact may also be determined, for example relating to oneor more of location, size, shape and distribution of the impact. Inother embodiments, a mechanical wave may be generated and monitored inorder to detect damage to the object 310, based on the propagationpattern of the wave. In exemplary embodiments the detection system 340may include a plurality of acoustic sensors, coupled, at various points,to the structured CNT network. The plurality of acoustic sensors may beused to detect a propagating acoustic signal and determine its originbased on sensor timing. In exemplary embodiments, an acoustic wave mayalso be monitored using the structured CNT network as anacoustic-electric transducer. The electrical signal equivalent of thewave signal may advantageously be isolated in the frequency domain. Anarray of detectors may be used to track the spatial propagation of thesignal. Acoustic wave applications are addressed in greater detail insections which follow.

In exemplary embodiments, the electrode arrays 320A and 320B may beadvantageously formed using a direct-write (DW) technique with aconductive material, for example, silver, onto a surface of the object310. FIGS. 4 and 5 illustrate example of DW traces. More particularly,FIG. 4 depicts exemplary DW traces produced using a plasma flame spray(see U.S. Pat. No. 5,278,442) where copper or ceramic materials areelectrically liquefied to be placed on the structure. FIG. 5 depictsexemplary DW traces produced using jetted atomized deposition (See U.S.Pat. No. 7,270,844) where silver or UV-curable epoxy are placed on astructure like an ink-jet printer and subsequently hardened. Thesereferences are incorporated herein to the extent they are notinconsistent with the present disclosure. DW technology advantageouslyenables a high level of electro-mechanical integration and facilitatescoupling electrodes to a structured CNT network, particularly, whereinterconnection problems would otherwise exist (for example, in theabsence of a free edge).

Modifications to DW techniques are also possible. For example, asilk-screening process may be improved to reduce trace resistancevariability and improve measurement accuracy. In some embodiments, achemical etched template may be used to apply a trace pattern withbetter precision. In other embodiments, the number of traces (orelectrodes) may be increased in order to increase spacial resolution(for example 32 horizontal (electrode rows) and 8 vertical (electrodecolumns). In exemplary embodiments, double-sided copper-coated-KAPTON(with coverlay) flexible circuit may be used to make connections withthe DW traces (as apposed to soldered wire connections). The flexiblecircuit may be bonded first to the object and then the DW tracesapplied, including overwriting of the flexible circuit (which may,advantageously, include alignment marks). In exemplary embodiments, aurethane coating may be applied to prevent oxidation. In someembodiments, the flexible circuit may be configured in the shape of arectangular frame, for example, with flaps on all 4 inside edgesincluding exposed pads for the DW process. The object can fit inside theframe window with the top and bottom flap overlapping onto the front ofthe FFRP, and the left and right flap overlapping on the back of theFFRP. Traces can then be routed along the edges of the frame to an 80pin ZIF connector located on a bottom tab for hardware connection. FIG.6 depicts an exemplary flexible frame, according to the presentdisclosure. The exemplary flexible frame may provide enhanced electricalcontinuity (greater reliability, durability and consistency) betweentraces and a detection or control system, specifically because it canmitigate contract resistance issues.

As described herein a printed circuit board (PCB) may be configured tocouple, e.g., with the flexible frame of FIG. 6. The PCB mayadvantageously include multiplexing switches, e.g., for multiplexing aplurality of channels (trace electrode pairs). The PCB may further beconfigured to couple with data acquisition hardware, a processor orcomputing environment. In exemplary embodiments, data may also becollected by hand, for example using a multimeter that can connect tothe PCB as well. The data may then be transferred, for example to aprocessor or other computing environment for further processing. Inother embodiments hardware, firmware and/or software may be implementedto automate the testing process (for example, automate selection andcycling of channels and/or data acquisition). In exemplary embodiments,automating hardware may connect directly to the flexible frame, forexample, via a mating surface mount technology (SMT) header connector,and to a PC, for example, via a RS-232 connection. Dual multiplexerbanks may be implemented to select an appropriate trace pair formeasurement. A constant current may then be applied through the tracepair and voltage (for example, 16-bit voltage) measured.Conductivity/resistivity may then be derived (note that resistance isdirectly related to voltage over current). The forgoing technique allowsfast measurement of traces. In tests conducted a total of 1140measurements (including data from both ends of traces to eliminateconstant offsets) were collected. Depending on settling time, test timemay be as fast as 1 second for all measurements.

Validation tests for conductivity/resistivity measurement were performedusing the embodiment depicted in FIG. 6. Each of three objects(specimens 1-3) were impacted at 15, 30 and 45 ft-lbs, with resistancedata collected between each trial. Overall, the results from the refinedsetup served the intended purpose of validating this technique anddemonstrating that the structured CNT network provides an excellentindication of barely visible impact damage (BVID). Furthermore, as canbe seen in FIG. 7, the overwhelming outcome was that with eachprogressive impact level additional breakage of CNT links caused anearly linear increase in peak percentage change of resistance value.

As evidenced in FIG. 7, for in-plane resistance, the first (15 ft-lb)impact caused barely perceivable, but repeatable changes of ˜10-20% inthe impact region. The second (30 ft-lb) impact caused ˜20-30%resistance change, and the final impact (45 ft-lb) ˜40-60% change.In-plane results also appeared to be more localized to the actualimpacted region, with clearly distinguishable damage patterns radiatingfrom the impact center. Once locked into place, the impact location forprogressive impacts on the same specimen was always in the samelocation, however, due to some play in the guiding system for thedropped weight the impact location specimen-to-specimen was not alwaysin the same location. This effect can be seen most dramatically bycomparing the second object (specimen 2), which had the best centralalignment, with the third object (specimen 3), which was impactedtowards the bottom edge. The specimen-to-specimen variability inmeasured damage was also likely influenced by the actual impact point,as a central impact would be more uniformly distributed in the specimenand cause less edge crushing.

For through-thickness results, the initial impact again caused smallchanges of ˜2-4%, with the second impact causing ˜4-8% changes and thefinal impact registering ˜8-10% changes. In this case, the pattern ofthe results appeared to be much less sensitive to impact location,likely because these were narrow specimens, however, the damage severitymeasured did seem dependant on the impact point. No visible damage waspresent in any of these cases, however testing on witness specimensindicated that the specimens would completely fracture between 50-60ft-lbs.

Acoustic Wave Detection:

In exemplary embodiments, a structured CNT network may be used to detectacoustic wave propagation in an object. In particular, a detectionsystem including a plurality of microphones, accelerometers, or otheracoustic sensors coupled at various points to the structured CNT networkmay be used to detect or “listen” for waves, e.g., high frequency stresswaves (e.g., 30-300 kHz) reverberating in the structure, for example,radiating from an impact point. Using the time synchronized results frommultiple sensors the generation point of the waves may be triangulated,for example in order to determine the impact point.

As noted above, acoustic wave detection may also be used as a possiblesolution for structured CNT network-based structural health monitoring,for example by exploiting the piezoresistive property of the CNTs.Essentially, as CNT fibers are strained by a stress wave, such as anacoustic wave, resistively dynamically proportionally to stress.Therefore, the response of a structured CNT-engineered material to animpact event can be captured through detection of a plurality of localCNT piezoresistive responses captured over a plurality of electrodepairs. It is noted that it may be advantageous to use a higher frequencyacquisition system. The plurality of local CNT responses enablesfull-field visualization of the waves as they propagate from the pointsource. This may allow easy detection and locating of damage. Inaddition, since this technique uses high frequency data (e.g., >30 kHz),it can be much less susceptible to static, structural dynamic operatingor acoustic loads, the effects of which can be filtered out in thefrequency domain.

A preliminarily proof of concept experiment was conducted successfullyto demonstrate the feasibility of this approach. Using a the smallundamaged electroded FFRC specimen, a constant current source and anoscilloscope were connected to pairs of electrodes on either extreme ofthe specimen, in order to monitor the dynamic voltage response on thesame time scale. Subsequently a pencil tip was broken in several placesalong the length of the specimen which would trigger the oscilloscope tocapture data by the slight jump in voltage. By comparing the relativearrival times of the voltage peaks measured from either end of thespecimen, the location of the pencil break could be easily determined.

Guided-Wave Detection

Relying on the piezoresistive property of the structured CNT network,Guided-Wave (GW) detection approaches may also be used. For example, asurface-bonded piezoelectric actuator may be used for high frequency GWexcitation of an object. The response of the structured CNT network maythen be captured (again advantageously using a higher frequencyacquisition system). This approach may enable full-field visualizationof a GW scatter field as it propagates.

Thermographic Techniques and De-Icing

As noted above, an object at least a portion of which is formed from orincludes a structured CNT-engineered material including a structured CNTnetwork may be coupled with a control system for providing power(voltage and/or current) to the structured CNT network so as to generateheat. Indeed, due to the nature of the CNTs having a reasonably lowelectrical resistance and high thermal conductivity, if a small voltage(such as 1-10 V) is applied across the structured CNT network (forexample, across any electrode pair) the structured CNT-engineeredmaterial can isothermally raise its temperature relevantly quickly (forexample, in seconds).

There are multiple advantages to the generating heart. Since structuralnon-uniformity can disrupt both the electrical and thermal flow inmaterial, conventional thermographic imaging techniques may be applied,for example, to detect damage to the object. The structured CNT networkfibers significantly enhances thermography by providing a fast internalheating source. For example, as seen in FIG. 8, a 2 V supply was placedacross various electrode pairs on a previously impacted specimen and athermal imaging camera was used to capture the response. As depicted,when the electrode pair away from the damage was utilized, nonon-uniformities were observed beyond local heating near the electrodes.Subsequently, when the probes were placed at the extremes of thespecimen, the impact damaged region became readily visible.

In other embodiments, generated heat may be used to heat the object ormaintain the object at or above a selected temperature. In someembodiments, the object may be heated so as to heat a substance by proxy(for example, to induce a phase transition thereof) or maintain asubstance at or above a selected temperature (for example to prevent aphase transition thereof). The substance may be external to a system,for example ice buildup, or internal to the system, for example fuel,coolant, etc). This may be particularly important to de-iceing, forexample wherein the control system is configured and/or programmed toheat the object so as to de-ice the object, or wherein the controlsystem is configured and/or programmed to maintain the object at orabove a selected temperature to prevent icing. In exemplary embodiments,a detection system may be included for providing temperature feedbackfor either the object or its surroundings. The control system may beconfigured and/programmed to adjust the power (current and/or voltage)based on the temperature feedback. In exemplary embodiments, thetemperature feedback may include a temperature rate of change, forexample, a heating rate of change or cooling rate of change (such asafter heating), for the object or for a substance heated by proxythereof. In some embodiments, the detection system may be configuredand/or programmed to determine, based on the temperature rate of change,a property or characteristic (for example, presence, amount,temperature, constitution/classification, or the like) of a substanceheated by the object. For example, the detection system may beconfigured and/or programmed to determine a presence (or absence) of asubstance, for example ice, on in or otherwise thermally coupled to theobject based on, for example a temperature change rate for the objectbeing less than a predetermined value. The detection may further beconfigured to determine an amount, for example a thickness, mass,volume, or the like, of the substance based on, for example thetemperature change rate for the object. In some embodiments, changes ina temperature change rate may be indicative of changes in an amount of asubstance. In other embodiments a temperature rate of change may becorrelated, for example, directly or indirectly, to the amount of asubstance. In some embodiments, a starting temperature may be consideredin conjunction with a temperature rate of change when determining theamount of a substance. Further exemplary embodiments for usingtemperature rate of change and experimental results are presented below.

Thermodynamic modeling may be used to demonstrate a correlation betweentemperature rate of change and substance amount. Consider, for example,a body comprised of n discrete materials immersed in a fluid oftemperature T₀. The body is heated by volumetric heating and cooled byconvective heat transfer. Placing a control volume around the system,the energy flow is given by the first law of thermodynamics:Ė _(in)(t)+Ė _(gen)(t)=Ė _(sto)(t)+Ė _(out)(t)  (1)

where t is time, Ė_(in)(t) is the rate of energy entering the controlvolume, Ė_(gen)(t) is the rate of energy generated within the controlvolume, Ė_(sto)(t) is the rate of energy stored within the controlvolume, and Ė_(out)(t) is rate of energy leaving the control volume. Letus assume that no energy is entering the control volume except throughvolumetric heating:

$\begin{matrix}{{{\overset{.}{E}}_{in}(t)} = {{0\mspace{14mu}{{\overset{.}{E}}_{gen}(t)}} = {\int\limits_{V}{{Q( {\overset{arrow}{x},t} )}d\; V}}}} & (2)\end{matrix}$

where Q is the volumetric heating rate and {right arrow over (x)} is theposition. If no phase transitions occur within the control volume, therate of energy stored is:

$\begin{matrix}{{{\overset{.}{E}}_{sto}(t)} = {\int\limits_{V}{\rho\mspace{14mu} c\frac{d\;{T( {\overset{arrow}{x},t} )}}{d\; t}d\; V}}} & (3)\end{matrix}$

where ρ is the mass density, and c is the specific heat per unit mass,and T is temperature. The rate of energy leaving the control volume isgiven by:

$\begin{matrix}{{{\overset{.}{E}}_{out}(t)} = {\int\limits_{A}{{{\overset{arrow}{q}( {\overset{arrow}{x},t} )} \cdot {\overset{arrow}{n}( \overset{arrow}{x} )}}d\; A}}} & (4)\end{matrix}$

where q is the heat flux vector, and n is the outward normal vector. Ifheat is lost only through convection, the normal heat flux is given by:{right arrow over (q)}({right arrow over (x)},t)·{right arrow over(n)}({right arrow over (x)})=h({right arrow over (x)})[T({right arrowover (x)},t)−T ₀]  (5)

where h is the convection coefficient. The system is initially atthermal equilibrium with ambient conditions. At time zero, a constantelectrical power P is applied to the body to heat it. Thus the rate ofenergy generated within the control volume equals the input electricalpower:Ė _(gen)(t)=P  (6)

Let us assume that the n discrete materials are infinitely conducting,and therefore the temperature of the body is independent of position.T({right arrow over (x)},t)=T(t)=  (7)

Also, let us assume that that the convection coefficient, density, andspecific heat are dependent only on the material number. With theseassumptions, the rate of stored and output energy terms, Equations 3 and4, are given by:

$\begin{matrix}{{{\overset{.}{E}}_{sto}(t)} = {{\lbrack {\sum\limits_{i = 1}^{n}\;{\rho_{i}\mspace{14mu} c_{i}\mspace{14mu} V_{i}}} \rbrack\frac{d\;{T(t)}}{d\; t}\mspace{14mu}{{\overset{.}{E}}_{out}(t)}} = {\lbrack {\sum\limits_{i = 1}^{n}\;{h_{i}\mspace{14mu} A_{i}}} \rbrack( {{T(t)} - T_{0}} )}}} & (8)\end{matrix}$

Where i subscript indicates the parameter is for the i^(th) material.Materials internal to the body have a convection coefficient of zerosince integration in Equation 4 is performed over the control area. Itshould be noted that the mass of material i is given by:m _(i) =V _(i)ρ_(i)  (9)

Solving Equation 1 for temperature, and using Equation 6-9:

$\begin{matrix}{{T(t)} = {T_{0} + {{P( {1 - e^{{- t}\;\lambda}} )}\text{/}{\sum\limits_{i = 1}^{n}\;{h_{i}\mspace{14mu} A_{i}}}}}} & (10)\end{matrix}$

where the exponential decay constant λ is given by:

$\begin{matrix}{\lambda = {\sum\limits_{i = 1}^{n}\;{h_{i}\mspace{14mu} A_{i}\text{/}{\sum\limits_{i = 1}^{n}\;{m_{i}\mspace{14mu} c_{i}}}}}} & (11)\end{matrix}$

It should be noted that the derivative of the temperature at time equalszero is given by:

$\begin{matrix}{ \frac{d\; T}{d\; t} |_{t = 0} = {P\text{/}{\sum\limits_{i = 1}^{n}\;{m_{i}\mspace{14mu} c_{i}}}}} & (12)\end{matrix}$

Note that Equation 12 is independent of the convection coefficient. Thustwo samples with different convection boundary conditions will have thesame initial slope, assuming the same power is applied. Consider twobodies starting at temperature T₀. and heated with power P. The firstbody has n materials, and the second body has one additional material.The ratio of the initial slope is given by:

$\begin{matrix}{\frac{ \frac{d\; T}{d\; t} \middle| {}_{t = 0}( {n\mspace{14mu}{materials}} ) }{ \frac{d\; T}{d\; t} \middle| {}_{t = 0}( {n + {1\mspace{14mu}{materials}}} ) } = {{\frac{P}{\sum\limits_{i = 1}^{n}\;{m_{i}\mspace{14mu} c_{i}}}\frac{\sum\limits_{i = 1}^{n + 1}\;{m_{i}\mspace{14mu} c_{i}}}{P}} = {1 + \frac{m_{n + 1}\mspace{14mu} c_{n + 1}}{\sum\limits_{i = 1}^{n}\;{m_{i}\mspace{14mu} c_{i}}}}}} & (13)\end{matrix}$

Since the specific heat and mass are greater than zero for allmaterials, the ratio in Equation 13 is greater than one. Thus the slope(temperature rate of change) decreases as an additional substance ormaterial (such as ice or water) is added to the body. This correlationmay be used to determine if and in what amount a substance or materialhas been added to a system.

To illustrate detection of ice using the above principles, temperatureas a function of time over the first thirty seconds for heatingspecimens of different ice thickness (no ice, 1, 2, and 3 mm) andstarting temperature (−5, −10 and −15° C.), is plotted in FIG. 9. Forthe first approximately twenty seconds of data, the temperature changerate appears nearly linear. The first twenty points of the temperaturedata was fitted to a line. The slope of this line (i.e. the temperaturerate of change) is plotted as a function of ice thickness in FIG. 10. Ascan be seen in FIG. 10, as the ice thickness increases the temperaturerate of change decreases, regardless of starting temperature (this waspredicted by Equation 13). For all samples with no ice, the temperaturerate of change is above 0.5° C./sec, which is indicated by the dashedhorizontal line. Temperature rate of change is also shown to bedependent on starting temperature which is not predicated in Equation13. Possible reasons include that the specific heat or convectioncoefficient is temperature dependent, or that there is a thermal lag inthe system which is not accounted for in the equations.

Based one the above results, a simple ice detection technique may beimplemented. A constant or near constant power (for example, 10 W) maybe supplied to a structured CNT network of an object and temperaturerate of change is calculated (for example, based on temperature as afunction time over the first fifteen seconds). In some embodiments, itmay be beneficial to discard data where temperature rate of change isless than 0.15° C. and use only the remaining data in calculatingtemperature rate of change. Ice is then detected if the temperaturechange rate is less than 0.5° C./sec. Exemplary implementation of theabove ice detection technique is illustrated in FIGS. 11 and 12. FIG. 11depicts an implementation where ice was detected. FIG. 12 depicts animplementation where no ice was detected.

De-icing tests were performed measuring temperature as a function oftime during the de-icing of specimens of varying ice thicknesses (waterdepth) and starting temperature (see Table 1 for specific parameters):

TABLE 1 De-icing test matrix Start temperature −5° C. −10° C. −15° C.Water 0 mm 3 tests 3 tests 3 tests depth 1 mm — — 3 tests 2 mm 3 tests 3tests 3 tests 3 mm 3 tests 3 tests 3 tests

The results of the deicing tests are depicted in FIG. 13. As can be seenin FIG. 13, as ice thickness increases the temperature change rate at agiven temperature decreases. Also of interest in FIG. 13 is de-icingtime which may be defined, for example, as the amount time it takes theobject to reach the melting point of a substance (0° C. for ice) or,alternatively, the amount time it takes the object reach a selectedtemperature above the melting point (for example, 5° C.). As depicted inFIG. 13, de-icing time increased as a function of thickness anddecreased as a function starting temperature.

In exemplary embodiments, power required to prevent a substance (forexample water), on, in or otherwise thermally coupled to an object, fromfreezing or re-refreezing may be determined. In particular, variouslevels of power may be applied to a structured CNT network of an objectto determine or maintain corresponding steady state temperatures forthat object (note that steady state temperature is not affected by thepresence or absence of ice). FIG. 14, depicts steady state temperatureas a function of power and power as a function of applied voltage for anexemplary object. Data was collected over a 30 minute period for eachpower level. As can be seen in FIG. 14, both the temperature versuspower and power versus applied voltage appear nearly linear.

As depicted in FIG. 14, the steady state temperature of 0° C.corresponded to approximately 1.81 W of power for the exemplary object.Anti-icing was tested using 2 W of power (steady state value ofapproximately 3° C.). Two types of tests were performed to investigateanti-icing performance; the first was anti-icing starting at 5° C.following cool down from room temperature, and the second was anti-icingstarting at 5° C. following warm-up (de-icing) from −5° C.). The resultsof the tests are depicted in FIG. 15. In each case the predicted steadystate temperature was achieved.

Additional Applications.

In exemplary embodiments, an object at least a portion of which isformed from or includes a structured CNT-engineered material having astructured CNT network may be used/configured as an antenna, forexample, for receiving, transmitting, absorbing or dissipatingelectromagnetic radiation, acoustic radiation or electrical discharge.Advantageously, the structured CNT network may be selectively structuredso as to optimize the structure, conductivity or other characteristic orproperty of the antenna for a given application or purpose. In exemplaryembodiments, the electromagnetic radiation may be a radio signal orradar signal, for example, wherein the structured CNT network isselectively patterned for radio detection/transmission and/or radardetection/dispersion. In other exemplary embodiments, the acousticradiation may from sound propagation, such as sonar, for example,wherein the structured CNT network is selectively patterned for sonardetection. In yet other exemplary embodiments the electrical dischargeor energy transfer may be a high power discharge, such as lightning, forexample, wherein the structured CNT network is selectively patterned forlightning dissipation.

In some embodiments an object at least a portion of which is formed fromor includes a structured CNT-engineered material having or includes astructured CNT network may be used/configured as a conduit for conveyingthermal or electrical energy, for example between a plurality ofcomponents coupled to the object. In exemplary embodiments, the coupledCNT network may be configured to provide power transfer from onecomponent (for example, from a solar power source) to another component.In other exemplary embodiments, the coupled CNT network may beconfigured provide a communication pathway between components. Inexemplary embodiments, based on the high thermal conductivity of thestructured CNT network, the object may be used as a heat sink orradiator panel. In other embodiments the object may be used as a heatshield or other thermal protecting device.

Machine Embodiments

It is contemplated that detection and control systems presented may beimplemented, in part, e.g., via one or more programmable processingunits having associated therewith executable instructions held on one ormore non-transitory computer readable medium, RAM, ROM, harddrive,and/or hardware. In exemplary embodiments, the hardware, firmware and/orexecutable code may be provided, e.g., as upgrade module(s) for use inconjunction with existing infrastructure (e.g., existingdevices/processing units). Hardware may, e.g., include components and/orlogic circuitry for executing the embodiments taught herein as acomputing process.

Displays and/or other feedback means may also be included to conveydetected/processed data. Thus, in exemplary embodiments, structuralhealth information, shape information, acoustic wave propagation,thermal information, etc. may be displayed, e.g., on a monitor. Thedisplay and/or other feedback means may be stand-alone or may beincluded as one or more components/modules of the processing unit(s). Inexemplary embodiments, the display and/or other feedback means may beused to visualize structural damage to an object.

The software code or control hardware which may be used to implementsome of the present embodiments is not intended to limit the scope ofsuch embodiments. For example, certain aspects of the embodimentsdescribed herein may be implemented in code using any suitableprogramming language type such as, for example, C or C++ using, forexample, conventional or object-oriented programming techniques. Suchcode is stored or held on any type of suitable non-transitorycomputer-readable medium or media such as, for example, a magnetic oroptical storage medium.

As used herein, a “processor,” “processing unit,” “computer” or“computer system” may be, for example, a wireless or wireline variety ofa microcomputer, minicomputer, server, mainframe, laptop, personal dataassistant (PDA), wireless e-mail device (e.g., “BlackBerry”trade-designated devices), cellular phone, pager, processor, faxmachine, scanner, or any other programmable device configured totransmit and receive data over a network. Computer systems disclosedherein may include memory for storing certain software applications usedin obtaining, processing and communicating data. It can be appreciatedthat such memory may be internal or external to the disclosedembodiments. The memory may also include non-transitory storage mediumfor storing software, including a hard disk, an optical disk, floppydisk, ROM (read only memory), RAM (random access memory), PROM(programmable ROM), EEPROM (electrically erasable PROM), etc.

Referring now to FIG. 9, an exemplary computing environment suitable forpracticing exemplary embodiments is depicted. The environment mayinclude a computing device 102 which includes one or more non-transitorymedia for storing one or more computer-executable instructions or codefor implementing exemplary embodiments. For example, memory 106 includedin the computing device 102 may store computer-executable instructionsor software, e.g. instructions for implementing and processing anapplication 120. For example, execution of application 120 by processor104 may facilitate detection of electrical conductivity across astructured CNT network.

The computing device 102 also includes processor 104, and, one or moreprocessor(s) 104′ for executing software stored in the memory 106, andother programs for controlling system hardware. Processor 104 andprocessor(s) 104′ each can be a single core processor or multiple core(105 and 105′) processor. Virtualization can be employed in computingdevice 102 so that infrastructure and resources in the computing devicecan be shared dynamically. Virtualized processors may also be used withapplication 120 and other software in storage 108. A virtual machine 103can be provided to handle a process running on multiple processors sothat the process appears to be using only one computing resource ratherthan multiple. Multiple virtual machines can also be used with oneprocessor. Other computing resources, such as field-programmable gatearrays (FPGA), application specific integrated circuit (ASIC), digitalsignal processor (DSP), Graphics Processing Unit (GPU), andgeneral-purpose processor (GPP), may also be used for executing codeand/or software. A hardware accelerator 119, such as implemented in anASIC, FPGA, or the like, can additionally be used to speed up thegeneral processing rate of the computing device 102.

The memory 106 may comprise a computer system memory or random accessmemory, such as DRAM, SRAM, EDO RAM, etc. The memory 106 may compriseother types of memory as well, or combinations thereof. A user mayinteract with the computing device 102 through a visual display device114, such as a computer monitor, which may display one or more userinterfaces 115. The visual display device 114 may also display otheraspects or elements of exemplary embodiments (for example, thermographicimages of an object. The computing device 102 may include other I/Odevices such a keyboard or a multi-point touch interface 110 and apointing device 112, for example a mouse, for receiving input from auser. The keyboard 110 and the pointing device 112 may be connected tothe visual display device 114. The computing device 102 may includeother suitable conventional I/O peripherals. The computing device 102may further comprise a storage device 108, such as a hard-drive, CD-ROM,or other storage medium for storing an operating system 116 and otherprograms, e.g., application 120 characterized by computer executableinstructions for implementing the detection and control systemsdescribed herein.

The computing device 102 may include a network interface 118 tointerface to a Local Area Network (LAN), Wide Area Network (WAN) or theInternet through a variety of connections including, but not limited to,standard telephone lines, LAN or WAN links (e.g., 802.11, T1, T3, 56 kb,X.25), broadband connections (e.g., ISDN, Frame Relay, ATM), wirelessconnections, controller area network (CAN), or some combination of anyor all of the above. The network interface 118 may comprise a built-innetwork adapter, network interface card, PCMCIA network card, card busnetwork adapter, wireless network adapter, USB network adapter, modem orany other device suitable for interfacing the computing device 102 toany type of network capable of communication and performing theoperations described herein. Moreover, the computing device 102 may beany computer system such as a workstation, desktop computer, server,laptop, handheld computer or other form of computing ortelecommunications device that is capable of communication and that hassufficient processor power and memory capacity to perform the operationsdescribed herein.

The computing device 102 can be running any operating system such as anyof the versions of the Microsoft® Windows® operating systems, thedifferent releases of the Unix and Linux operating systems, any versionof the MacOS® for Macintosh computers, any embedded operating system,any real-time operating system, any open source operating system, anyproprietary operating system, any operating systems for mobile computingdevices, or any other operating system capable of running on thecomputing device and performing the operations described herein. Theoperating system may be running in native mode or emulated mode.

FIG. 10 illustrates an exemplary network environment 150 suitable for adistributed implementation of exemplary embodiments. The networkenvironment 150 may include one or more servers 152 and 154 coupled toclients 156 and 158 via a communication network 160. In oneimplementation, the servers 152 and 154 and/or the clients 156 and/or158 may be implemented via the computing device 102. The networkinterface 118 of the computing device 102 enables the servers 152 and154 to communicate with the clients 156 and 158 through thecommunication network 160. The communication network 160 may includeInternet, intranet, LAN (Local Area Network), WAN (Wide Area Network),MAN (Metropolitan Area Network), wireless network (e.g., using IEEE802.11 or Bluetooth), etc. In addition the network may use middleware,such as CORBA (Common Object Request Broker Architecture) or DCOM(Distributed Component Object Model) to allow a computing device on thenetwork 160 to communicate directly with another computing device thatis connected to the network 160.

In the network environment 160, the servers 152 and 154 may provide theclients 156 and 158 with software components or products under aparticular condition, such as a license agreement. The softwarecomponents or products may include one or more components of theapplication 120. For example, the client 156 may detect electricalconductivity data which is subsequently communicated over the server 152for processing.

Although the teachings herein have been described with reference toexemplary embodiments and implementations thereof, the disclosed systemsare not limited to such exemplary embodiments/implementations. Rather,as will be readily apparent to persons skilled in the art from thedescription taught herein, the disclosed systems are susceptible tomodifications, alterations and enhancements without departing from thespirit or scope hereof. Accordingly, all such modifications, alterationsand enhancements within the scope hereof are encompassed herein.

What is claimed is:
 1. An apparatus comprising: an object having aportion formed from a carbon nanotube (CNT) engineered material having aCNT network formed of a first plurality of CNTs bound to one another byattraction or entanglement to form a self-supporting sheet free of asupport material prior to contact with a matrix material, the CNTnetwork conducts electricity to maintain or change a temperature of theportion of the object in a predetermined temperature pattern, whereinthe first plurality of CNTs are distributed to form a contiguous networkof CNTs; a first electrical contact coupled to a first portion of theCNT network; a second electrical contact coupled to a second portion ofthe CNT network; and wherein the first electrical contact and the secondelectrical contact are couplable to a control system configured orprogrammed to drive the CNT network with electrical energy to generateheat across the CNT network in the pre-determined temperature pattern.2. The apparatus of claim 1, wherein the CNT network has a structuredform to define a geometry for the material and allow physicalmanipulation thereof.
 3. The apparatus of claim 1, wherein the controlsystem drives the CNT network with the electrical energy to increase ormaintain a temperature of a substance associated with the object at orabove a selected temperature.
 4. The apparatus of claim 1, wherein thecontrol system drives the CNT network with the electrical energy toincrease the temperature of the portion of the object so as to de-icethe portion of the object or prevent icing on the portion of the object.5. The apparatus of claim 1, wherein the control system drives the CNTnetwork with the electrical energy to increase the temperature of theportion of the object to prevent icing thereof.
 6. The apparatus ofclaim 1, wherein the control system drives the CNT network with theelectrical energy to increase the temperature of the portion of theobject to melt a frozen fluid or prevent a fluid from freezing.
 7. Theapparatus of claim 1, further comprising a detection system forproviding temperature feedback for at least one of the object or itssurroundings.
 8. The apparatus of claim 7, wherein the electrical energyfrom the control system is adjustable based on the temperature feedback.9. The apparatus of claim 7, wherein the temperature feedback indicatesa temperature rate of change for an interior or exterior portion of theobject or for a substance heated by the object.
 10. The apparatus ofclaim 9, wherein the detection system determines an amount of ice on theexterior portion of the object based on the temperature rate of change.11. The apparatus of claim 7, wherein the detection system detects aphase change of a substance on a surface of the object based on changesin electrical conductivity or resistance across the CNT network.
 12. Theapparatus of claim 1, wherein the first plurality of CNTs in the CNTnetwork interact with a second plurality of CNTs in the CNT network toprovide a contiguity between the first and second pluralities of CNTs.13. The apparatus of claim 1, wherein an electrical conductivity of theapparatus is between 10⁻⁴ S/mm and 10⁻¹ S/mm.
 14. A system comprising:an object having a portion formed from a carbon nanotube (CNT)engineered material having a CNT network formed of a first plurality ofCNTs bound to one another by attraction or entanglement to form aself-supporting sheet free of a support material prior to contact with amatrix material, the CNT network conducts electricity, wherein the firstplurality of CNTs are distributed to form a contiguous network of CNTs;a first electrical contact coupled to a first portion of the CNTnetwork; a second electrical contact coupled to a second portion of theCNT network; and a configurable or programmable detection systemcouplable to the first electrical contact and the second electricalcontact to detect a change in a physical property or characteristicrelated to a change in structure of the object, based on a measurementacross a portion of the CNT network; wherein detecting the change in thephysical property or the characteristic includes detecting at least oneof: (i) a change in electrical conductivity or resistance across theportion of the CNT network or (ii) a propagation of an acoustic waveacross a portion of the object.
 15. The system of claim 14, wherein theCNT network has a structured form to define a geometry for the materialand allow physical manipulation thereof.
 16. The system of claim 14,wherein the physical property or characteristic is related to structuralhealth of the object, and wherein the structural change to the CNTnetwork is on account of damage to the object.
 17. The system of claim14, wherein the physical property or characteristic is related to ashape of the object, and wherein the structural change to the CNTnetwork is on account of a change in the shape of the object.
 18. Thesystem of claim 17, wherein the shape of the object is configurable, andwherein the detection system provides feedback on the shape of theobject.
 19. The system of claim 14, wherein the detection system iscouplable to the CNT network via one or more electrode arrays defining aplurality of electrode pairs across the CNT network.
 20. The system ofclaim 19, further comprising one or more multiplexers for combiningmeasurements from the plurality of the electrode pairs.
 21. The systemof claim 14, wherein the detection system detects a phase change of asubstance on a surface of the object based on changes in electricalconductivity or resistance across the CNT network.
 22. A method forcontrolling the temperature of an object, the method comprising:providing an object having a portion formed from a carbon nanotube (CNT)engineered material having a CNT network formed of a plurality of CNTsbound to one another by attraction or entanglement to form aself-supporting sheet free of a support material prior to contact with amatrix material, the CNT network conducts electricity, wherein theplurality of CNTs are distributed to form a contiguous network of CNTs,wherein the object includes: a first electrical contact coupled to afirst portion of the CNT network; and a second electrical contactcoupled to a second portion of the CNT network; providing a controlsystem operationally couplable to the first electrical contact and thesecond electrical contact; and instructing the control system to drivethe CNT network with electrical energy to generate heat across the CNTnetwork so as to maintain or change a temperature of the object in apre-determined temperature pattern.
 23. The method of claim 22, whereinthe CNT network has a structured form to define a geometry for thematerial and allow physical manipulation thereof.
 24. The method ofclaim 22, further comprising instructing the control system to drive theCNT network with electrical energy to generate heat to increase ormaintain a temperature of a substance associated with the object at orabove a selected temperature.
 25. The method of claim 24, whereinincreasing or maintaining a temperature of the substance is configuredto affect a phase change in the substance.
 26. The method of claim 22,further comprising instructing the control system to drive the CNTnetwork with electrical energy to increase the temperature of the objectso as to de-ice a portion of the object or prevent icing on a portion ofthe object.
 27. The method of claim 22, further comprising instructingthe control system to drive the CNT network with electrical energy toincrease the temperature of a portion of the object to melt a frozenfluid in the system or prevent a fluid in the system from freezing. 28.The method of claim 22, further comprising detecting temperaturefeedback for at least one of the object and its surroundings, whereinthe control system adjusts the electrical energy based on thetemperature feedback.
 29. The method of claim 22, further comprisingdetermining a property or characteristic of a substance heated by theobject based on a temperature rate of change for at least a portion ofthe object or for the substance heated by the object.
 30. A method forde-icing or preventing icing of an object, the method comprising:providing an object having a portion formed from a carbon nanotube (CNT)engineered material having a CNT network formed of a first plurality ofCNTs bound to one another by attraction or entanglement to form aself-supporting sheet free of a support material prior to contact with amatrix material, the CNT network conducts electricity to maintain orchange a temperature of the portion of the object in a predeterminedtemperature pattern, wherein the first plurality of CNTs are distributedto form a contiguous network of CNTs, wherein the object includes: afirst electrical contact coupled to a first portion of the CNT network;and a second electrical contact coupled to a second portion of the CNTnetwork; providing a control system operationally couplable to the firstelectrical contact and the second electrical contact; and instructingthe control system to drive the CNT network with electrical energy togenerate heat across the CNT network so as to increase the temperatureof the object in the pre-determined temperature pattern, so as to de-iceat least the portion of the object or prevent icing on the portion ofthe object.